ISO 3443-4:1986 建物の公差—パート4：アセンブリの偏差を予測し、公差を割り当てる方法 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting.

International Standard ISO 3443/4 was prepared by Technical Committee ISO/TC 59, Building construction.

Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated.

0 Introduction

This part of ISO 3443 forms one of a series concerning tolerances for building and building components.

It should be read in conjunction with ISO 3443/1, ISO 3443/2, ISO 1803/1 and ISO 1803/2.

Parts 3 and 4 of ISO 3443 have been produced to meet the need for internationally agreed methods of relating accuracy, tolerances and fit in the determination of sizes for components and construction (and, in ISO 3443/4, joints). Two distinct needs are identified, though both share common ground.

There is thus a need to provide generally applicable expressions relating accuracy, tolerances and fit, that can be drawn upon, either:

• a) to identify optimum target sizes for standard components, where each type of component has a variety of applications, or
• b) to identify appropriate limits of size for components, whether standard or not, for application in a specific building.

Both needs can be met by expression of substantially the same relationships between the factors affecting fit, and in principle either standard might be pressed into service to meet either aim. In practice, however, each is structured to serve its particular purpose.

Joints in more than one dimension are however only considered in this part of ISO 3443.

Part 3 of ISO 3443 is structured to meet the aims in a) above. It provides procedures for selecting target sizes (formerly"work sizes") for components, or in situ works, such that joint clearances will be within their required limits with a known probability of success. ¹⁾ The procedures deal with the relationship between the following factors:

• 1) accuracy of components and in situ work;
• 2) sizes of components and in situ work;
• 3) joint clearances;
• 4) probability of fit;

and they can be used whether 2), 3) or 4) above is the unknown to be calculated. The procedures assume that values for 1) above have been established by measurement surveys and relate target sizes to co-ordinating sizes using the concepts of"extension" and"deduction" ; see 4.4 and 4.5.

The procedures also enable a target size to be calculated for any standard component, such that the component will have an optimal probability of fit in all its applications.

Worked examples are given in annex B.

ISO 3443/4 is structured to meet the needs in b) above. It is therefore concerned primarily with the design of buildings in which components (including standard components) are used, and is aimed primarily at building designers who, as engineers, can be expected to be mathematically and statistically competent. It is to meet these aims that this part of ISO 3443 deals with

• methods for predicting deviations and specifying tolerances to obtain a particular desired total accuracy in an assembly,
• the effect of specified tolerances on expected size variability,
• the basis for optimization of tolerances for each particular assembly and its elements.

ISO 3443/4 presupposes calculations only for assemblies with elements of one dimension, such as beams and columns, for the sake of simplicity. However, tables for common cases with elements of two and three dimensions (panels, etc.) are given in the annex.

1 Scope

This part of ISO 3443 indicates some general principles and one method for predicting deviations in composite systems and specifying tolerances for the constituent elements in order to meet functional requirements and tolerance specifications for the assembly.

4 Definitions

For the purpose of this part of ISO 3443, the definitions given in ISO 1791 and ISO 1803/1 apply with the following additions.